The etiology of a large number of birth defects is unknown and probably multifactorial. Maternal zinc deficiency has been implicated as a causative factor in several birth defects. However, at the time of diagnosis of the birth defect, if is usually difficult, if not impossible, to determine the adequacy of the maternal zinc status during the development of the malformed embryonic parts. This project will attempt to demonstrate maternal zinc deficiency by studying the zinc content of tooth enamel formed during embryonic life. After preliminary animal studies on tooth enamel from rats fed zinc deficient diets, we will section exfoliated primary teeth of healthy control subjects and subjects with congenital anomalies, i.e., cleft lip and/or palate and spina bifida. The sectioning will be done in such a manner as to separate out fragments of enamel that calcified at approximately the same time as the development of the embryonic organs of interest. We will then examine the zinc content of the tooth enamel using atomic absorption spectrophotometry. We will analyze for differences within individual teeth as well as between groups of subjects.